diff --git a/ext/dom/internal_helpers.h b/ext/dom/internal_helpers.h
index b74a735ad2e..95f49d5f480 100644
--- a/ext/dom/internal_helpers.h
+++ b/ext/dom/internal_helpers.h
@@ -18,8 +18,8 @@
 #define DOM_INTERNAL_HELPERS
 
 /* We're using the type flags of the zval to store an extra flag. */
-#define DOM_Z_OWNED(z, v)   ZVAL_PTR(z, (void *) v)
-#define DOM_Z_UNOWNED(z, v) ZVAL_INDIRECT(z, (void *) v)
+#define DOM_Z_OWNED(z, v)   ZVAL_PTR(z, (void *) (v))
+#define DOM_Z_UNOWNED(z, v) ZVAL_INDIRECT(z, (void *) (v))
 #define DOM_Z_IS_OWNED(z)   (Z_TYPE_P(z) == IS_PTR)
 
 #ifdef DOM_CE_H